Nb3Sn Fabrication and Sample Characterization at Cornell<br />Sam Posen, Matthias Liepe, Yi Xie, N. Valles<br />Cornell Un...
Outline<br />Motivation<br />A little theory<br />Wuppertal Method<br />Wuppertal Results<br />Activities at Cornell<br />...
Motivation<br />SRF cavity preparation techniques have improved from years of R&D<br />Cavity gradient is approaching fund...
SRF cavity preparation techniques have improved from years of R&D<br />Cavity gradient is approaching fundamental limit se...
Theory<br />Tc higher so Q0 is higher than for Nb at same T<br />GL Theory predicts Hsh = 0.75Hc, κ large<br />But GL Theo...
Progress<br />Theory indicates gradients of 120 MV/m for perfect Nb3Sn, 200 MV/m for perfect MgB2<br />Perfect Nb should g...
Wuppertal Method<br />A crucible of tin is heated in an evacuated chamber<br />Evaporated tin coats the connected cavity<b...
Wuppertal Method - Details<br />(1) Initial heating at 200°C and degassing<br />(2) Nucleation at 500°C and heating for 5 ...
Wuppertal Results – 1996<br />From Padamsee [4]<br />Best CW result shown – High Q0!! Great potential<br />However, Q-slop...
Wuppertal Results – 1997<br />Pulsed measurements done at Cornell with Wuppertal cavity<br />Maybe cavity coating not perf...
New Materials at Cornell<br />Restarting Nb3Sn work at Cornell – older work gives hope for promising results<br />2010 pul...
2010 Test of Wuppertal Nb3Sn Cavity<br />Retested after 20 years on shelf and unknown history<br />Cornell Data (N. Valles...
2010 Test of Wuppertal Nb3Sn Cavity<br />Cornell Data (N. Valles) with Wuppertal cavity<br />
Cornell Nb3Sn Furnace Insert<br />Compatible with existing single cell UHV furnace<br />Start with samples<br />Tin in cru...
Sample Furnace<br />Manufacturing almost complete<br />Almost all parts in hand<br />Hoping for first coating by end of mo...
Cavity Furnace<br />Plan to weld full cavities into furnace insert<br />EP cavities after weld<br />Cut cavities out after...
Pillbox TE Cavity<br />Takes sample plates OR small samples<br />In commissioning phase<br />Plans exist to test MgB2 from...
Pillbox TE Cavity – Small Samples<br />TE011, f = 6 GHz     <br />Hmax, sample /Hmax, cavity ~ 0.64<br />sample radius = 0...
Mushroom TE Cavity<br />TE012, f = 4.78 GHz     <br />Hmax, sample /Hmax, cavity ~ 1.24<br />sample radius = 5 cm <br />De...
Current status and future plans<br />Current status:<br />Fabrication of small sample pillbox TE cavity done<br />EP, 800C...
Summary<br />Nb3Sn is good candidate for reaching gradients >50 MV/m<br />Wuppertal method for coating cavities using vapo...
Call for Samples!<br />If you have any samples you would like to try in an RF test<br />3.5 cm or 0.25 cm radius for the p...
References<br />[1] G. Arnolds-Mayer, “A15 surfaces in Nb cavities,” Proc. SRF2, Geneva, Switzerland, pp. 643-666, 1984.<b...
Wuppertal Papers<br />P.Boccard et al. “Results from Some Temperature Mapping Experiments on Nb3Sn RF Cavities”, Proc. SRF...
Upcoming SlideShare
Loading in...5
×

Posen - Nb3Sn Fabrication and Sample Characterization at Cornell

941

Published on

http://www.surfacetreatments.it/thinfilms

Nb3Sn Work at Cornell (Sam Posen - 30')
Speaker: Sam Posen - Cornell Unviersity | Duration: 30 min.
Abstract
This paper will describe the active research program at Cornell University devoted to superconducting Nb3Sn coatings. This includes a new furnace system for coating 5-inch diameter niobium samples using the vapor diffusion technique, designed after the systems built at Wuppertal University. The first coated samples have undergone surface studies as well as RF tests conducted with a newly constructed TE cavity. The results will be presented. Once the coating procedure is optimized, Nb3Sn-coated cavities will be fabricated at Cornell, and both CW and pulsed measurements will be done. Recently, a cavity coated at Wuppertal more than 20 years ago was tested using these techniques. The results will be shown here.

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
941
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
15
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide
  • Most of you are probably aware of these points, but for the sake of painting a complete picture, let me take us a step back a moment and look at some m
  • What does theory tell us about nb3sn?
  • First will optimize coating parameters with samples
  • Used to have to groove sample for mode splitting – now flat sample
  • Moved port from center because fields were weak
  • Posen - Nb3Sn Fabrication and Sample Characterization at Cornell

    1. 1. Nb3Sn Fabrication and Sample Characterization at Cornell<br />Sam Posen, Matthias Liepe, Yi Xie, N. Valles<br />Cornell University<br />Thin Films Workshop<br />Presented October 5th 2010<br />By Sam Posen<br />In Padua, Italy<br />
    2. 2. Outline<br />Motivation<br />A little theory<br />Wuppertal Method<br />Wuppertal Results<br />Activities at Cornell<br />From Arnolds-Mayer (1984) [1]<br />
    3. 3. Motivation<br />SRF cavity preparation techniques have improved from years of R&D<br />Cavity gradient is approaching fundamental limit set by superheating field (Hsh) of niobium<br />As beam energy demands continue to rise, accelerators will have to become longer<br />ILC calls for tens of km, thousands of cavities<br />Higher gradients = $$$$$$ savings<br />Higher Q0s for CW and at high gradients pulsed = $$$$$$ savings<br />
    4. 4. SRF cavity preparation techniques have improved from years of R&D<br />Cavity gradient is approaching fundamental limit set by superheating field (Hsh) of niobium<br />As beam energy demands continue to rise, accelerators will have to become longer<br />ILC calls for tens of km, thousands of cavities<br />Higher gradients = $$$$$$ savings<br />Higher Q0s for CW and at high gradients pulsed = $$$$$$ savings<br />Motivation<br />Nb3Sn promises to give both!<br />
    5. 5. Theory<br />Tc higher so Q0 is higher than for Nb at same T<br />GL Theory predicts Hsh = 0.75Hc, κ large<br />But GL Theory is valid only near Tc<br />Eilenberger equations give behaviour at lower temperature [Catelani and Sethna, PRB (2008) [2]]<br />(Assuming large κ, temp = 2K)<br />
    6. 6. Progress<br />Theory indicates gradients of 120 MV/m for perfect Nb3Sn, 200 MV/m for perfect MgB2<br />Perfect Nb should give ~55 MV/m<br />Years of research has led to reproducible >30 MV/m in accelerator structures<br />After much R&D, new materials may outperform Nb<br />Some research has already gone into Nb3Sn<br />Best performance from vapor diffusion technique at Wuppertal U. in 1990s (G. Mueller, M. Peiniger, et al. – see references)<br />
    7. 7. Wuppertal Method<br />A crucible of tin is heated in an evacuated chamber<br />Evaporated tin coats the connected cavity<br />The temperatures of the tin and the cavity are controlled independent of each other<br />SnCl2 is used to nucleate growth sites early on<br />1100°C<br />1200°C<br />Adapted from Dasbach et al. (1989) [3]<br />
    8. 8. Wuppertal Method - Details<br />(1) Initial heating at 200°C and degassing<br />(2) Nucleation at 500°C and heating for 5 hrs<br />(3) Growth at 1100°C (cavity) and 1200°C (tin source) for 3 hrs<br />(4) Tin heating off but cavity still hot for 30 mins (avoid surplus Sn)<br />From Arnolds-Mayer (1984) [1]<br />
    9. 9. Wuppertal Results – 1996<br />From Padamsee [4]<br />Best CW result shown – High Q0!! Great potential<br />However, Q-slope at ~5 MV/m typical for Wuppertal tests<br />Max field then: Eacc ~15 MV/m (600 Oe) – need higher Q0’s at medium field level CW, and higher fields pulsed<br />EP, baking may help to mitigate problems<br />Thermometry and surface studies can also help find any weak spots in coating<br />
    10. 10. Wuppertal Results – 1997<br />Pulsed measurements done at Cornell with Wuppertal cavity<br />Maybe cavity coating not perfect everywhere<br />GL Theory Prediction<br />From T. Hays [5]<br />
    11. 11. New Materials at Cornell<br />Restarting Nb3Sn work at Cornell – older work gives hope for promising results<br />2010 pulsed high power test of Wuppertal Nb3Sn cavity<br />Fabrication of Nb3Sn coatings on samples<br />Planned fabrication of Nb3Sn coatings on cavities<br />Pillbox TE cavity<br />Mushroom TE cavity<br />
    12. 12. 2010 Test of Wuppertal Nb3Sn Cavity<br />Retested after 20 years on shelf and unknown history<br />Cornell Data (N. Valles) with Wuppertal cavity<br />
    13. 13. 2010 Test of Wuppertal Nb3Sn Cavity<br />Cornell Data (N. Valles) with Wuppertal cavity<br />
    14. 14. Cornell Nb3Sn Furnace Insert<br />Compatible with existing single cell UHV furnace<br />Start with samples<br />Tin in crucible at bottom of insert<br />Heater brings tin to higher temp than sample<br />Thermocouples for temp measurement<br />S.S.<br />Nb<br />
    15. 15. Sample Furnace<br />Manufacturing almost complete<br />Almost all parts in hand<br />Hoping for first coating by end of month<br />
    16. 16. Cavity Furnace<br />Plan to weld full cavities into furnace insert<br />EP cavities after weld<br />Cut cavities out after coating, HPR, and test<br />Use thermometry and Cornell OST quench detection to locate any weak areas<br />Dissect cavities so that surface studies can be performed on weak areas<br />Use this feedback to improve coating technique<br />
    17. 17. Pillbox TE Cavity<br />Takes sample plates OR small samples<br />In commissioning phase<br />Plans exist to test MgB2 from X. Xi (Temple)<br />Groove to separate frequencies of TE011 and TM110 modes<br />Demountable sample bottom plate<br />TE011, f = 6 GHz Hmax, sample /Hmax, cavity ~ 0.8 sample radius = 3.5 cm <br />
    18. 18. Pillbox TE Cavity – Small Samples<br />TE011, f = 6 GHz <br />Hmax, sample /Hmax, cavity ~ 0.64<br />sample radius = 0.25 cm <br />small round sample plate<br />Additional port to keep symmetry<br />
    19. 19. Mushroom TE Cavity<br />TE012, f = 4.78 GHz <br />Hmax, sample /Hmax, cavity ~ 1.24<br />sample radius = 5 cm <br />Demountable sample bottom plate<br />TE013, f = 6.16 GHz <br />Hmax, sample /Hmax, cavity ~ 1.57<br />sample radius = 5 cm <br />
    20. 20. Current status and future plans<br />Current status:<br />Fabrication of small sample pillbox TE cavity done<br />EP, 800C & 120C bake, HRP of pillbox TE cavity done<br />No multipacting from TRACK3P simulation for mushroom TE cavity coupler design<br />Test plans and schedule:<br />Pillbox TE cavity commissioning<br />New mushroom-type high gradient TE cavities ready for first tests in early next year<br />Collaboration: Send us your samples! <br />
    21. 21. Summary<br />Nb3Sn is good candidate for reaching gradients >50 MV/m<br />Wuppertal method for coating cavities using vapor diffusion is being attempted at Cornell<br />Furnace insert for coating samples is almost ready<br />Pillbox TE cavity commissioning<br />Mushroom TE cavity being built<br />Call for samples!<br />
    22. 22. Call for Samples!<br />If you have any samples you would like to try in an RF test<br />3.5 cm or 0.25 cm radius for the pillbox TE cavity;<br />5 cm radius for the mushroom TE cavity;<br />Email Matthias Liepe, mul2 at cornell.edu<br />
    23. 23. References<br />[1] G. Arnolds-Mayer, “A15 surfaces in Nb cavities,” Proc. SRF2, Geneva, Switzerland, pp. 643-666, 1984.<br />[2] G. Catelani and J. Sethna, “Temperature dependence of the superheating field for superconductors in the high-κ London limit,” Phys. Rev. B., 78 224509, 2008.<br />[3] G. Dasbach et al. “Nb3Sn coating of high purity Nb cavities,” IEEE Transactions on Magnetics, vol. 25, no. 2, pp. 1862-1864, 1989.<br />[4] H. Padamsee, J. Knobloch, and T. Hays, RF Superconductivity for Accelerators Wiley & Sons, New York, ISBN 0-471-15432-6, 1998.<br />[5] T. Hays and H. Padamsee, “Measuring the RF critical field of Pb, Nb, and Nb3Sn,”Proc. SRF 1997, Padova, Italy, pp. 789-794.<br />Y. Xie et al. “Design of a TE-type cavity for testing superconducting material samples,” SRF09, Berlin, Germany, pp.281-285, 2009.<br />
    24. 24. Wuppertal Papers<br />P.Boccard et al. “Results from Some Temperature Mapping Experiments on Nb3Sn RF Cavities”, Proc. SRF8, Abano Terme, Italy, pp.795-813, 1997.<br />G Müller et al. “Nb3Sn layers on high purity Nb cavities with very high quality factors and accelerating gradients,” Proc. EPAC96,Barcelona, Spain, pp. 2085-2087, 1996.<br />M. Peiniger et al. “Work on Nb3Sn cavities at Wuppertal,” Proc. SRF3, Argonne, pp. 503-532, 1988.<br />G. Dasbach et al. “Nb3Sn coating of high purity Nb cavities,” IEEE Transactions on Magnetics, vol. 25, no. 2, pp. 1862-1864, 1989.<br />M. Peiniger et al. “Nb3Sn for superconducting accelerators at 4.2 K,” Proc. EPAC88, Rome, Italy, pp. 1295-1297, 1988.<br />G. Arnolds-Mayer. “A15 surfaces in Nb cavities,” Proc. SRF2, Geneva, Switzerland, pp. 643-666, 1984.<br />
    1. A particular slide catching your eye?

      Clipping is a handy way to collect important slides you want to go back to later.

    ×